• 한국토양비료학회지
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• 제49권5호
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• pp.510-516
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• 2016

Soil respiration has been recognized as a key factor of the change of organic matter and fertility due to the carbon and nitrogen mineralization. In this study, we evaluated the effect of soil respiration on the light fraction-C and inorganic N content depending on temperature in soil applied with organic matter. Soil respiration was calculated by using total $CO_2$ flux released from soil applied with $2Mg\;ha^{-1}$ of rice straw compost and rye for 8 weeks incubation at 15, 25, $35^{\circ}C$ under incubation test. After incubation test, light fraction and inorganic N content were investigated. Rye application dramatically increased soil respiration with increasing temperature. $Q_{10}$ value of rye application was 1.69, which was higher 27% than that of rice straw compost application. Light-C and $NO_3-N$ contents were negatively correlated to soil respiration. Light-C in rye application more decreased than that in rice straw compost with temperature levels. These results indicate that temperature sensitivity of soil respiration could affect soil organic mater content and N availability in soil due to carbon availability. Also, light fraction would be useful indicator to evaluate decomposition rate of organic matter in soil under a short-term test.

• 한국토양비료학회지
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• 제40권5호
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• pp.400-404
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• 2007

본 연구는 밭 토양에 계분, 돈분, 우분 및 톱밥을 혼용하여 부숙시킨 계분톱밥,돈분톱밥 및 우분톱밥퇴비 등 성상이 상이한 가축분퇴비 6종을 각각 매 년 $3ton\;C\;ha^{-1}$를 4년간 연용한 토양에서 탄소 분획 변화를 파악하고자 실시하였다. 가축분퇴비 4년 연용 후 토양 탄소함량의 증가율은 톱밥을 혼용하지 않은 계분, 돈분 및 우분퇴비 시용구는 25-30% 증가 한 반면, 우분톱밥퇴비구(COMS)를 비롯한 톱밥혼용퇴비 처리구 증가율은 40%를 상회하였다. Light Fraction(LF)의 탄소함량 변화는 모든 처리구에서 2년차 이후 급격히 증가하는 추세를 보였으며, 반면, Heavy Fraction(HF)의 탄소함량은 톱밥 혼용퇴비보다 순수 가축분퇴비를 연용한 처리구가 증가량이 많았다. 이러한 결과는 톱밥이 혼용된 가축분 퇴비보다 톱밥을 혼용하지 않은 순수가축분 퇴비가 분해보다 빠름으로 인해 비교적 안정된 탄소형태로의 전환도 많아졌다고 사료된다.

• 청정기술
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• 제29권4호
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• pp.262-271
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• 2023

전 세계적으로 폐플라스틱 발생에 따른 환경적 문제로 인해 이를 처리하기 위한 다양한 연구가 진행되고 있다. 이 중 폐플라스틱을 열분해하여 연료 및 원료 등으로 재활용하는 방법이 보편적이다. 본 연구에서는 '폐플라스틱 열분해유(WPPO)의 나프타 원료로 활용'을 목적으로 총 5종의 폐플라스틱 열분해유(WPPO)의 물성분석을 통해 나프타 원료로 사용이 가능한지 살펴봄과 동시에 넓은 비점범위로 인해 분리정제 기술 중 하나인 감압증류를 통해 light fraction과 heavy fraction으로 분획 및 GC-VUV로 paraffin, 올레핀 함량 및 기타 화합물 등의 구성성분을 나타내었다. 그 결과, WPPO의 원료, 분획에 상관없이 높은 올레핀 함량이 나타났고 방향족 및 paraffin 함량 등은 원료에 따라 차이가 발생하였고 산소 및 기타 화합물도 원료 및 분획별 차이가 큰 것으로 나타났다. 또한, light fraction은 나프타와 유사한 탄소분포를 나타내지만, heavy fraction은 탄소분포가 C₁₁ ~ C₁₄로 나타났다. 결론적으로, 폐플라스틱 열분해유의 나프타원료 활용을 위해서 추가 공정이나 원료 선별 등이 필요할 것으로 판단된다.

• 대한기계학회논문집
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• 제7권4호
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• pp.372-378
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• 1983

Use of dual phase steel are growing for its high strength and light weight in automobiles. The effect of the martensite volume fraction with various impact velocities on the strength, ductility and absorbed energy of dual phase (ferrite-martensite) steels were investigated in low carbon 1.5% Mn steels which were soaked at 700.deg. C, 730.deg. C, 780.deg. C, and brine quenched. Both the yield load and the maximum impact load increased when the martensite volume fraction increased, the loading time and the absorbed energy of the specimen decreased when the martensite volume fraction increased.

• 한국주조공학회지
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• 제12권2호
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• pp.149-154
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• 1992

The wetting behaviour of SiC/Al-Li composite interface has been investigated by using an infiltration method. The critical pressure for melt infiltration into SiC particulate preform has been determined by measuring the melt infiltration distance changes with the variation of applied pressure. The threshold pressure of pure Al, Al-0.2wt%Li, Al-0.5wt%Li for melt infiltration are 3.94, 3.93, $3.7Kg/cm^2$ respectively, which implies a slight improvement in wettability of SiC/Al composite by addition of Li. The threshold pressure for melt infiltration also changes with the variation of other parameters such SiC particulate size, SiC particulate fraction and melt temperature.

• 천문학회지
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• 제33권2호
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• pp.89-95
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• 2000

As an efficient method to detect blending of general gravitational microlensing events, it is proposed to measure the shift of source star image centroid caused by microlensing. The conventional method to detect blending by this method is measuring the difference between the positions of the source star image point spread function measured on the images taken before and during the event (the PSF centroid shift, ${\delta}{\theta}$c,PSF). In this paper, we investigate the difference between the centroid positions measured on the reference and the subtracted images obtained by using the difference image analysis method (DIA centroid shift, ${\delta}{\theta}$c.DIA), and evaluate its relative usefulness in detecting blending over the conventional method based on ${\delta}{\theta}$c,PSF measurements. From this investigation, we find that the DIA centroid shift of an event is always larger than the PSF centroid shift. We also find that while ${\delta}{\theta}$c,PSF becomes smaller as the event amplification decreases, ${\delta}{\theta}$c.DIA remains constant regardless of the amplification. In addition, while ${\delta}{\theta}$c,DIA linearly increases with the increasing value of the blended light fraction, ${\delta}{\theta}$c,PSF peaks at a certain value of the blended light fraction and then eventually decreases as the fraction further increases. Therefore, measurements of ${\delta}{\theta}$c,DIA instead of ${\delta}{\theta}$c,PSF will be an even more efficient method to detect the blending effect of especially of highly blended events, for which the uncertainties in the determined time scales are high, as well as of low amplification events, for which the current method is highly inefficient.

• 신재생에너지
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• 제5권4호
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• pp.52-58
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• 2009

Upgrading of pyrolysis wax oil using HZSM-5 catalyst has been conducted in a continuous fixed bed reactor at $450^{\circ}C$, 1hour, LHSV 3.5/h. The catalytic degradation was studied with a function of catalyst amount and reaction temperature. The raw pyrolysis wax oil shows relatively high boiling point distribution ranging from around $300^{\circ}C$ to $550^{\circ}C$, which has considerably higher boiling point distribution than that of commercial diesel. The catalytic degradation using HZSM-5 catalyst shows the high conversion of pyrolysis wax oil to light hydrocarbons. The liquid product obtained shows high gasoline range fraction as around 90% fraction and considerably high aromatic fraction in liquid product. Here, the experimental variable such as catalyst amount and reaction temperature was influenced on the product distribution.

• 한국안전학회지
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• 제25권6호
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• pp.9-13
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• 2010

An experimental study for characteristics of soot were conducted at the post-flame region in jet diffusion flames, where carbon dioxide was used as additives in oxidizer stream. Light-extinction method was performed using He-Ne laser with wave length at 632.8nm for the measurement of relative soot density and soot volume fraction with dimensionless extinction coefficient, $K_e$ and mass specific extinction coefficient, ${\sigma}_s$. To increase of resolution, laser light was modified for sheet-form using concave, convex lenses and slit. C/H ratio was introduced for quantitative analysis of soot growth which is expressed by carbonization and dehydrogen. Also transmission electron microscopy(TEM) was used for observation of morphological shape. The results show that the relative soot density in the post-flame region was lower when carbon dioxide was added in oxidizer stream because of reduction of flame temperature.

• 한국토양비료학회지
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• 제44권6호
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• pp.1314-1319
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• 2011

This study was carried out to investigate the surface soil organic carbon fractions affecting by different land use types, including needle-leaf forest (FN), broad-leaf forest (FB), pasture, annual upland cropping land (upland), and paddy rice land (paddy). We chose seven regions across Korean inland, considering sea level altitude, and measured soil organic carbon content and physico-chemical properties such as bulk density at a depth of 0~15 cm using core samples in April for the each land use type. In addition, labile organic carbon fractions in soil including light fraction and hot water extractable carbon were investigated. From this study, organic carbon storage (Mg C per ha) in the upper 15-cm soils was highest in FB (37.8), and decreased in the order of pasture (29.1), FN (28.8), paddy (21.9), and upland crop (19.9). In forest, more than 20% of soil organic carbon existed as light fraction, the free organic matter. Hot-water extractable carbon contents of soils in five land use types were lower than 7% of their soil organic carbon content.

• 생약학회지
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• 제29권1호
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• pp.22-27
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• 1998

This study was carried out to develop antitumor agents based on effects of the ethyl acetate soluble fraction of the methanolic extract of Lonicerae flos on human oral epitheloid carcinoma cells. Human oral epitheloid carcinoma cells were cultured in RPMI-1640 media containing 10% fetal bovine serum, antibiotic, and fungizone. After incubation for 24 hrs, the cells were treated with A, B, C, D, and E fractions for 48hrs under the same condition. MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazoliumbromide), NR (Neutral red) and SRB (Sulforhodamine B protein) assay were performed. The light microscopic findings were observed by inverted microscope. In MTT assay, fraction B was shown significant antitumor activity (P<0.001), fraction E was shown significant antitumor activities (P<0.05), but the other fractions were not shown. In NR assay, fraction B was shown significant antitumor activity (P<0.001). In SRB assay, fractions B was shown significant antitumor activities (P<0.01). fractions A and D were shown significant antitumor activities (P<0.05). but the other fractions were not shown. In light microscopy. the fraction B of the ethyl acetate soluble fraction of the methanolic extract of Lonicerae flos showed the highest antitumor activity. These finding suggested that fraction B possessed the most antitumorous agent.